Method for determining the efficacy of a decontamination procedure

Abstract

A method determines an efficacy of a decontamination procedure. The method includes providing a test object and a control object. The test object is contaminated with a first known amount of inoculum comprising microorganisms. The control object is contaminated with a second known amount of the inoculum. The first known amount of inoculum and the second known amount of inoculum are substantially the same. The decontamination procedure is performed on the contaminated test object but not on the contaminated control object. The microorganisms from the decontaminated test object and the contaminated control object are recovered. A number of microorganisms recovered from the decontaminated test object is compared with a number of microorganisms recovered from the contaminated control object. The decontamination procedure is deemed effective when the number of microorganisms recovered from the decontaminated test object is at least 3 logs less than the number of microorganisms recovered from the contaminated control object.

What is claimed is:  
     
       1. A method for determining an efficacy of a decontamination procedure, the method comprising the steps of: 
       providing at least one test object and at least one control object;  
       contaminating multiple sites on each of the at least one test object and the at least one control object with a known amount of an inoculum comprising organisms;  
       performing the decontamination procedure on the at least one test object but not on the at least one control object;  
       recovering the microorganisms from each of those respective contaminated sites on the at least one decontaminated test object and the at least one contaminated control object;  
       comparing a number of microorganisms recovered from each respective site of the at least one decontaminated test object with a number of microorganisms recovered from each respective site of the at least one contaminated control object; and  
       deeming the decontamination procedure effective when the number of microorganisms recovered from each site of the test object is at least approximately a 3 log reduction of the number of microorganisms recovered from each respective site of the control object.  
     
     
       2. The method of  claim 1 , wherein said at least one test object and said at least one control object are substantially identical prior to performing said method. 
     
     
       3. The method of  claim 2 , wherein said at least one test object and said at least one control object are surgical instruments. 
     
     
       4. The method of  claim 2 , wherein some of said test and control sites are on external surfaces of said test and control objects and a balance of said test and control sites are internal surfaces of said test and control objects. 
     
     
       5. The method of  claim 2 , wherein said at least one test object and said at least one control object are endoscopes. 
     
     
       6. The method of  claim 2 , further comprising verifying that said at least one test object site and said at least one control object site have been contaminated with said inoculum. 
     
     
       7. The method of  claim 1 , wherein at least three of said test object and at least three of said control object are provided. 
     
     
       8. The method of  claim 1 , wherein said inoculum further comprises an organic soil. 
     
     
       9. The method of  claim 8 , wherein said organic soil contains blood serum. 
     
     
       10. The method of  claim 9 , wherein said microorganisms are selected from the group consisting of  Bacillus stearothermophilus  and  Mycobacterium terrae.    
     
     
       11. The method of  claim 10 , wherein an amount of said microorganisms in said known amount of inoculum is at least 10 8  CFU. 
     
     
       12. The method of  claim 1 , wherein said inoculum further comprises British soil. 
     
     
       13. The method of  claim 12 , wherein said microorganisms are selected from the group consisting of  Bacillus stearothermophilus  and  Mycobacterium terrae.    
     
     
       14. The method of  claim 13 , wherein an amount of said microorganisms in said known amount of inoculum is at least 10 8  CFU. 
     
     
       15. The method of  claim 1 , wherein said microorganisms are selected from the group consisting of  Bacillus stearothermophilus  and  Mycobacterium terrae.    
     
     
       16. The method of  claim 15 , wherein an amount of said microorganisms in said known amount of inoculum is at least 10 8  CFU. 
     
     
       17. The method of  claim 1 , wherein an amount of said microorganisms in said known amount of inoculum is at least 10 8  CFU. 
     
     
       18. The method of  claim 1 , wherein said decontamination procedure is cleaning, and said cleaning is determined to be effective when said number of microorganisms recovered from each respective site of said at least one test object is about 3 logs less than said number of microorganisms recovered from each respective site of said at least one control object. 
     
     
       19. The method of  claim 18 , wherein said known amount of inoculum is tagged for counting. 
     
     
       20. The method of  claim 1 , wherein said decontamination procedure is disinfection, and said disinfection is determined to be effective when said number of microorganisms recovered from each respective site of said at least one test object is about a 6 log reduction of said number of microorganisms recovered from each respective site of said at least one control object. 
     
     
       21. The method of  claim 20 , wherein said microorganisms are resistant mycobacteria. 
     
     
       22. The method of  claim 1 , wherein said decontamination procedure is sterilization, and said sterilization is determined to be effective when said number of microorganisms recovered from each respective site of said at least one test object is about a 12 log reduction of said number of microorganisms recovered from each respective site of said at least one control object. 
     
     
       23. The method of  claim 22 , wherein said microorganisms are bacterial endospores. 
     
     
       24. The method of  claim 1 , wherein said efficacy of said decontamination procedure is compared with said efficacy of a different decontamination procedure determined by said method. 
     
     
       25. A method for determining the efficacy of a decontamination procedure, comprising the steps of: 
       providing at least one test instrument and at least one control instrument, said instruments being substantially identical and having a plurality of multiple sites comprising internal and external sites in or on which microorganisms reside;  
       contaminating said multiple sites of said test instrument with a first known starting amount of inoculum comprising microorganisms and contaminating said multiple sites of said control instrument with a second known starting amount of the same inoculum, the first known starting amount of inoculum and the second known starting amount of inoculum being substantially the same, said contamination being applied to all said sites associated with said test and control instruments;  
       performing a decontamination procedure on said contaminated sites of said test instrument but not on said contaminated sites of said control instrument;  
       separately recovering microorganisms from each of those respective contaminated sites associated with said decontaminated test instrument and said contaminated control instrument;  
       comparing the amount of microorganisms recovered from each respective site in the decontaminated test instrument with the amount of microorganisms recovered from each respective site in the contaminated control instrument, and ascertaining the efficacy of the decontamination procedure employed.  
     
     
       26. A method according to  claim 25 , wherein the decontamination procedure is deemed effective relative to the sampling technique when the amount of microorganisms recovered from each site of the decontaminated test instrument is at least 3 logs less than the amount of microorganisms recovered from each site of the contaminated control instrument. 
     
     
       27. A method according to  claim 26 , wherein said surgical instrument is an endoscope. 
     
     
       28. A method according to  claim 25 , wherein the first sampling technique and the second sampling technique are one of direct microbiologic sampling techniques and indirect microbiologic sampling techniques. 
     
     
       29. A method according to  claim 28 , wherein the direct microbiologic sampling techniques include one of swabbing and brushing and the indirect microbiologic sampling techniques include one of flushing or rinsing with a sterile fluid. 
     
     
       30. A method according to  claim 25 , further comprising the step of determining the number of microorganisms recovered from the test and control instruments. 
     
     
       31. A method according to  claim 28 , further comprising the step of comparing the number of microorganisms recovered from the sites of the control instrument to the number of microorganisms applied initially to these sites and to determine efficacy of the first and second sampling techniques. 
     
     
       32. A method according to  claim 25 , wherein said instruments are reusable surgical instruments. 
     
     
       33. A method according to  claim 25 , wherein the first and second known amounts of inoculum comprise at least 1×10 8  colony forming units. 
     
     
       34. A method according to  claim 33 , wherein the step of recovering the microorganisms from the contaminated control instrument is at least 1×10 6  colony forming units. 
     
     
       35. A method according to  claim 34 , further comprising the step of permitting the inoculum to dry before performing the decontamination step.